Calculation of Mixture Statistics Using Popstats - Promega

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Assumptions Hardy Weinberg Equilibrium No allele dropout Individuals are unrelated Population substructure is negligible Contributors are of the same race But also, unlike conventional frequency reporting… We have to address specific hypotheses
Two common questions are generally asked: How often would a random person be excluded as a contributor to the observed mixture ? (Exclusion Probability) What statistical support is there for any postulated hypothesis of the origin of the mixture? (Likelihood)
Page 1 and 2: Popstats Unplugged 14 th Internatio
Page 3 and 4: What Constitutes a DNA Mixture? Pr
Page 5 and 6: What Constitutes a DNA Mixture? Ci
Page 7 and 8: Common Mixture Interpretations Alle
Page 9: But, before we begin… Calculation
Page 13 and 14: Exclusion Probability This is a mea
Page 15 and 16: For example: Exclusion Probability
Page 17 and 18: Exclusion Probability The probabili
Page 19 and 20: Exclusion Probability In presence o
Page 21 and 22: Exclusion Probability What does thi
Page 23 and 24: We have the following data: Mixture
Page 25 and 26: Given that both victim and suspect
Page 27 and 28: What if we couldn’t assume H-W? P
Page 29 and 30: How does PopStats handle this calcu
Page 31 and 32: Here is the input data But what is
Page 33 and 34: It is the compliment of Inclusion P
Page 35 and 36: PE = 1 - 8.033 X 10 -7 = 0.99999919
Page 37: What if we have to consider some al
Page 40 and 41: Mixtures and Likelihood Ratios Like
Page 42 and 43: Let’s use the same example used i
Page 44 and 45: Three Alleles Victim is heterozygot
Page 46 and 47: The prosecution may postulate that
Page 48 and 49: The defense might argue that the fo
Page 50 and 51: The defense might argue that the fo
Page 52 and 53: Since the victim has the profile (8
Page 54 and 55: Now here is where the “RATIO” i
Page 56 and 57: Defense hypothesis 2 is a little mo
Page 58 and 59: How do we get these probabilities?
Page 60 and 61:
Of course…we could incorporate θ
Page 62 and 63:
What next… The total probability
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HOW TO EXPRESS THE NUMBERS FROM LIK
Page 66 and 67:
Conservative Basic True!
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Or The probability (chance) that th
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Assumptions In Likelihood Computati
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Assumptions In Likelihood Computati
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So, lets go back to our previous da
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And our "K1" and "K2" genotypes:
Page 78 and 79:
Our entry data from before:
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This side will autofill when changi
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C2 reflects the H a H a = The resul
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Notes: • The layout screen is pos
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Ok… so what do we get when we pus
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Big Number Names: • 1,000,000 mil
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You could also look at what the all
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C2 reflects the H a H a = The resul
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You can drag and drop the entire fi
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Continue, holding the SHIFT button
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Big Number Names: • 1,000,000 mil
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Lets look at a different scenario O
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Two alleles match the suspect - A 1
Page 104 and 105:
The prosecution may postulate that
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The defense might argue that the fo
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The resulting likelihood ratio is:
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So, with regard to Defense Hypothes
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Same question as before but… Thre
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Under the Prosecution’s hypothesi
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Unk 1 Unk 2 A1A2 A1A2 A1A2 A1A3 A1A
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The Likelihood Ratio becomes: p 3 2
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p 1 = 0.1, p 2 = 0.2, and p 3 = 0.3
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So, with regard to the Defense Hypo
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Of course we can do this in PopStat
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Of course we can do this in PopStat
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Now…Let's have some real fun! Sce
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Our Knowns: Let's see how this scen
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H a1 = The results are explained by
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Our Results:
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The "profile" in C1 represents all
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Our Results:
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Considerations Unlike interpretatio
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Considerations Most critical step o
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Calculation of Mixture Statistics Using Popstats - Promega

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